Various designs of apparatus for countercurrent chromatography have been previously proposed. One such earlier design, disclosed in U.S. Pat. No. 4,051,025, to Y. Ito, used a slowly rotating coiled tube to perform preparative-scale countercurrent extraction with two-phase solvent systems. Another earlier system, shown in U.S. Pat. No. 4,058,460, to Y. Ito, employs a horizontal flow-through centrifuge which is capable of performing a similar partitioning process by slowly rotating the coiled column in the gravitational field.
The system disclosed in U.S. Pat. No. 4,051,025 employs a pair of rotating seals, which often produce complications such as leakage of the solvents and contamination by air bubbles, thereby limiting the capability of the apparatus. Although the system of U.S. Pat. No. 4,058,460 eliminates the use of rotating seals, it subjects the coiled column to an uneven centrifugal force field, which tends to interface with the efficient mixing of the two phases; also, in this second system, when multiple large-bore coiled columns are to be mounted, this necessitates a large amount of space because the apparatus must employ a large counterweight mounted on one side of the rotary frame for providing the required dynamic balance for the apparatus.
There is a definite need for overcoming the disadvantages of the previously used systems.